578. 
GEOPHYSICS: L. A. BAUER 
Proc. N. a. S. 
of the magnets producing the records are chiefly mechanical in their origin.^ 
8. Terrestrial Magnetism and Electricity, and Physical Oceanography: 
The problems of joint interest to the two sections relate to the magnetic 
and electric observations over the oceans, the delineation of disturbed 
regions, especially near ports, the effect of ocean depths on changes of 
the magnetic elements as observed over the surface, etc. 
9. Terrestrial Magnetism and Electricity, and Volcanology: Besides 
local changes in the distribution of the earth's magnetic forces in the 
neighborhood of volcanic eruptions, there are other points of joint in- 
terest to students of volcanology and of terrestrial magnetism and elec- 
tricity. As an illustration may be cited the remarkable circumstance 
of a world-wide magnetic disturbance which took place almost simul- 
taneously over the entire earth, beginning at 7 h. 54 m. St. Pierre local 
mean time on May 8, 1902. According to the reports at the time of the 
Mont Pelee eruption the town clock at St. Pierre was found stopped at 
7 h. 50 m. ; how accurately this clock kept local mean time is, of course, 
not known and it may be that the time as obtained from the magnetic 
records will have to be regarded as the most accurate determination of 
the beginning of that remarkable eruption. Magnetic disturbances oc- 
curred again during the eruptions of May 20 and May 21, 1902. 
At the meeting of the "Congress of Arts and Science," held at St. Louis, 
1904, ly. A. Bauer gave a preliminary discussion of the magnetic disturb- 
ances just referred to in connection with his paper on "The Present 
Problems of Terrestrial Magnetism."^ The precise causal connection, if 
any, between the Mont Pelee eruption and the magnetic disturbance 
has not been completely worked out at present. The connection may 
have to be sought through the fact that there were remarkable electric 
phenomena during the eruption which may have caused a sufficient change 
in the electrification, or in the electric currents, of the earth's atmosphere 
to have produced in turn a magnetic effect. 
During the eruption of Krakatoa, Java, of 1883, there was no world- 
wide magnetic disturbance. However, a local disturbance, of discon- 
tinuous character, occurred at the near-by Batavia Magnetic Observatory, 
this disturbance lasting merely during the rain of volcanic ashes upon 
Batavia, and the magnetic effect was attributed by the director of the 
Batavia Observatory to the magnetic character of the ashes. The elec- 
tric phenomena in connection with the Krakatoa eruption were also very 
marked and changes of interest to students in terrestrial electricity may 
have occurred. 
The question of electric currents in the earth's crust in connection with 
volcanic eruptions is also a matter of interest. Thus Palmieri^ made 
earth-current observations in the vicinity of Vesuvius during the period 
1889-1893. His observations seemed to show a parallelism with the 
